Pain-related cerebral potentials in response to acute painful electrical stimulation in sheep.
OBJECTIVE
To examine associations between late event-related cerebral potential amplitudes and behavioural responses to noxious electrical stimulation as an indicator of acute pain in sheep.


METHODS
Analysis of variance for the effects of stimulus intensity on the behaviour and event-related cerebral potential variables.


METHODS
Ninety-six brief constant current electrical pulse trains were presented to the front left leg of eight sheep at four intensities (2.5 to 10 mA) in a randomised order. An event-related cerebral potential and a graded flinch response were recorded for each stimulus and the 24 event-related cerebral potentials at each intensity were averaged to produce a mean waveform. Various components of this waveform were analysed and changes in these measures and the sheep's flinch response, as stimulus intensity increased, were determined.


RESULTS
Both the flinch response and some event-related cerebral potential components, that is, peak amplitudes 114 [N1], 187 [P1], 318 [P2] and 230 [Pm] ms after stimulus onset, were significantly affected as stimulus intensity increased.


CONCLUSIONS
These corresponding behavioural and event-related cerebral potential changes indicate the usefulness of using changes in the event-related cerebral potential to measure acute pain in sheep.
Morris
J P
JP
Victorian Institute of Animal Science, Werribee.
Ong
R M
RM
O'Dwyer
J K
JK
Barnett
J L
JL
Hemsworth
P H
PH
Clarke
I J
IJ
Jongman
E C
EC
D000704:Analysis of Variance; D000827:Animal Welfare; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001921:Brain / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography / Q000379:methods / Q000662:veterinary; D005071:Evoked Potentials / Q000502:physiology*; D008297:Male; D010146:Pain / Q000503:physiopathology / Q000662:veterinary*; D011897:Random Allocation; D012756:Sheep; D012757:Sheep Diseases / Q000503:physiopathology*